Total points for return flights higher than sum of individual flight point values?

[b_adger]

Hi,
Just looking at booking some flights with my velocity points. I notice that the total points value is 300 higher than the sum of the individual flights points values.

Example: economy reward ADL-BNE = 12100 points, BNE-ADL = 11800 (total 23900) but the total appears at 24200 points.
If I select the business rewards, 21400 and 21100, total comes out at 42800 instead of the correct 42500.

Anyone seen this before?